Study On The Preparations Of Sr SrAl₂O₄:Eu²⁺,Dy³⁺ Luminescence Materials By Liquid Phase Methods

The rare earth doped strontium aluminate luminescent materials are widely used in the field of illumination,display and fluorescence labeling,owing to the properties of safe,non-toxic,high luminous intensity and long service life.The strontium aluminate luminescent materials are always prepared by solid state method,which have large particles and should be ground before using.However,the luminous efficiency of the materials often reduced after grinding.So it is important to explore a simple and energy-saving method to synthesize SrAl₂O₄:Eu²⁺,Dy³⁺with ultrafine particles,uniform size distribution and good luminescence performance.In this paper,we prepared SrAl₂O₄:Eu²⁺,Dy³⁺luminescent materials by liquid phase method,which include of sol-gel method,hydrothermal method,microwave-hydrothermal method and electrostatic spinning method.The influences of different methods on the crystal structures,particle sizes,morphologies and luminescence performances of the materials were studied.And the main contents are as follows:?1?The preparation of SrAl₂O₄:Eu²⁺,Dy³⁺and SrAl₂O₄:Eu²⁺by sol-gel method.The effects of pH value of the precursor solution,the heat treatment conditions and the amount of Eu²⁺and Dy³⁺ions on the structures and luminescent properties of the products were studied.The results indicated that the pH value of the precursor solution was critical to the formation of the sol and gel,and the optimum pH value was 1.The optimal heat treatment condition of the dry gels was determined:They were pretreated at 800?for 4 h in air,and then heated at 1300?for 2 h in the atmosphere of 95%Ar+5%H₂,and the obtained products showed a monoclinal structure of?-SrAl₂O₄ phase.When the doping amount of Eu²⁺and Dy³⁺were 1%and 4%?mol ratio?respectively,the obtained SrAl₂O₄:Eu²⁺,Dy³⁺sample exhibited high fluorescence intensity and long afterglow performance,and the afterglow time of the sample was about 1 h.When the sample was only doped with Eu²⁺and the doping amount was 3%,the obtained SrAl₂O₄:Eu²⁺exhibited the best mechanoluminescent performence in this paper.?2?The preparation of SrAl₂O₄:Eu²⁺,Dy³⁺by hydrothermal method.The effects of the reaction time,the amount of precursor solution,the solvent,surfactant,the reaction temperatures and time on the morphologies and luminescent properties of the materials were discussed.When Span80 was chose as the surfactant,H₂O as the solvent,and the doping amount of Eu²⁺and Dy³⁺were 1%and 4%respectively,the hydrothermal product was obtained at 220?for 24 h.It has a leaf-like structure and well dispersed with the size of about 1?m.When the leaf-like product was then heat treated,the obtained SrAl₂O₄:Eu²⁺,Dy³⁺sample were?-Sr Al₂O₄ phase with monoclinal structure,and it exhibited the highest fluorescence intensity in this paper.?3?The preparation of SrAl₂O₄:Eu²⁺,Dy³⁺by microwave-hydrothermal method.When H₂O was as the solvent and in the absence of any surfactant,the doping amount of Eu²⁺and Dy³⁺were 1%and 4%respectively,the product was obtained at 120?for 2 h.And then it was heat treated,the final product of SrAl₂O₄:Eu²⁺,Dy³⁺with monoclinal structure showed the best long afterglow performance in this paper,and its afterglow time can reach about 4 h.?4?The one-dimensional nanostructures of SrAl₂O₄:Eu²⁺,Dy³⁺were successfully prepared by electrostatic spinning method.And the one-dimensional nanostructures of SrAl₂O₄:Eu²⁺,Dy³⁺@SnO₂ and SrAl₂O₄:Eu²⁺,Dy³⁺@SiO₂ were prepared by coaxial co-spinning method.The morphologies of the above samples still maintained after heated at 1150?for 2 h.When SnO₂ was used as the shell,the products had a good flexibility,which emitted green light with the maximum peak at 510 nm.When SiO₂ was used as the shell,SrAl₂Si₂O₈ phase was generated in the sample,and it emitted blue light with the maximum peak at 425nm.